St. Laurent-class destroyer

St. Laurent-class destroyer
HMCS Fraser (DDH 233) in 1983
Class overview
Name:	St. Laurent
Builders:	Canadian Vickers, Burrard Yarrows, Halifax Shipyards, Marine Industries
Operators:
Preceded by:	Prestonian-class frigate
Succeeded by:	Restigouche-class destroyer
In commission:	29 Oct 1955 - 5 Oct 1994
Planned:	14
Completed:	7
Lost:	2
Preserved:	1
General characteristics
Type:	Destroyer Escort
Displacement:	As DDE: 2263 tons (normal), 2800 tons (deep load) As DDH: 2260 tons (normal), 3051 tons (deep load)
Length:	371 ft (113.1 m)
Beam:	42 ft (12.8 m)
Draught:	As DDE: 13 ft (4.0 m) As DDH:14 ft (4.3 m)
Propulsion:	2-shaft English-Electric geared steam turbines, 3 Babcock and Wilcox boilers 30,000 shp
Speed:	28.5 knots (52.8 km/h)
Range:	4,750 nautical miles (8,797.0 km) at 14 knots (25.9 km/h)
Complement:	As DDE: 249 As DDH: 213 plus 20 aircrew
Sensors and processing systems:	As DDE: 1 x SPS-12 air search radar 1 x SPS-10B surface search radar 1 x Sperry Mk.2 navigation radar 1 x SQS-10 or -11 hull mounted active search and attack sonar 1 x SQS-501 (Type 162) high frequency bottom profiling sonar 1 x SQS-502 (Type 170) high frequency Limbo mortar control sonar 1 x UQC-1B "Gertrude" underwater telephone 1 x GUNAR (Mk.64 GFCS with 2 on-mount SPG-48 directors) As DDH: 1 x SPS-12 air search radar 1 x SPS-10B surface search radar 1 x Sperry Mk.2 navigation radar 1 x URN 20 TACAN radar 1 x SQS-10 or -11 hull mounted active search and attack sonar 1 x SQS-501 (Type 162) high frequency bottom profiling sonar 1 x SQS-502 (Type 170) high frequency Limbo mortar control sonar 1 x SQS-504 VDS, medium frequency active search (except 233 after 1986) 1 x UQC-1B "Gertrude" underwater telephone 1 x GUNAR (Mk.64 GFCS with 1 on-mount SPG-48 director)
Electronic warfare & decoys:	As DDE: 1 x DAU HF/DF (high frequency direction finder) As DDH: 1 x WLR 1C radar warning 1 x UPD 501 radar detection 1 x SRD 501 HF/DF
Armament:	As DDE: 2 x 3"/50 Mk.33 FMC twin mounts guns 2 x 40mm "Boffin" single mount guns 2 x Mk NC 10 Limbo ASW mortars 2 x single Mk.2 "K-gun" launchers with homing torpedoes As DDH: 1 x 3"/50 Mk.33 FMC twin mount gun 1 x Mk NC 10 Limbo ASW mortar 2 x triple Mk.32 12.75 inch launchers firing Mk.44 or Mk.46 Mod 5 torpedoes
Aircraft carried:	As DDE: none As DDH: 1 x CH-124 Sea King
Aviation facilities:	As DDE: none As DDH: 1 x midships helicopter deck with Beartrap and hangar
Notes:	Ships in class include: HMCS St. Laurent (DDH 205),HMCS Saguenay (DDH 206),HMCS Skeena (DDH 207),HMCS Ottawa (DDH 229),HMCS Margaree (DDH 230),HMCS Fraser (DDH 233),HMCS Assiniboine (DDH 234)

The St. Laurent class destroyer was a class of destroyers that served the Royal Canadian Navy and later the Canadian Forces from the mid-1950s to the mid-1990s.

This was the first major class of warship designed and built in Canada. They were similar to the British Type 12 Whitby class frigate, but used more American equipment than British. There were seven ships of the class commissioned between 1955 and 1957.

They were originally intended as destroyer escorts (DDE) but were later refitted and reclassed as destroyer helicopter escorts (DDH).

Construction

The need for the St. Laurent class came about in 1949 when Canada joined NATO and the Cold War was in its infancy. The RCN was assigned responsibility for anti-submarine warfare and controlling sea space in the western $3.

Design work for a new class of destroyer escorts began that year with the original completion date slated for 1955. They were designed by Montreal naval architects German and Milne "under the direction of a senior constructor, Sir Rowland Baker, seconded from the [British] Director of Naval Construction... Baker produced a design basically similar to the Whitby [Type 12], but incorporating several ideas of his own....To flatter Canadian susceptibilities, Baker was careful to make the appearance as different as possible from the Whitby, but the ship that resulted was virtually a Type 12 specification (albeit with a different hull form) translated by a different design team."

The St Laurent class were "built to an operational requirement much like that which produced the British Type 12, and powered by the same machinery plant, she was strikingly different. The rounded deck-edge forward was adopted to prevent ice forming." She was designed to operate in harsh Canadian conditions. They were built to counter nuclear, biological and chemical attack conditions, which lead to a design with a rounded hull, a continuous main deck, and the addition of a pre-wetting system to wash away contaminants. The living spaces on the ship were part of a "citadel" which could be sealed off from contamination for the crew safety. The ships were sometimes referred to as "Cadillacs" for their relatively luxurious crew compartments; these were also the first Canadian warships to have a bunk for every crew member since previous warship designs had used hammocks.

Other innovative features not found on other ships of its time included an operations room separate from the bridge, from which the captain could command the ship while in combat, 12 separate internal telephone systems, air conditioning, and the latest advances in radar and sonar technology.

The St. Laurent class originally called for 14 vessels to be commissioned no later than 1955; however, changing design specifications due to the rapidly changing Cold War naval environment, as well as Canada's wartime priorities during the Korean War, saw only the first 7 completed by 1957. The remaining 7 vessels were built as the follow-on Restigouche-class to incorporate advancements in naval warship design in the preceding years. There were also two essentially similar follow-on classes, the Mackenzie Class (4 ships completed 1962-63) and the Annapolis Class (2 ships, completed 1964), the latter completed as helicopter carrying destroyer escorts from the onset, and not converted later as were the seven St Laurent Class ships.

Armament

The St. Laurent class was fitted with twin 3 inch/L50 guns for engaging both surface and air targets. Her anti-submarine armament consisted of a pair of triple barrelled Limbo ASW mortars in a stern well. The stern well had a roller top to close it off from following seas. "As in the case of the Type 12, the design included provision for long-range homing torpedoes (in this case BIDDER [Mk 20E] or the US Mark 35. They were never fitted however."

As built, the twin 3-inch 50-calibre anti-aircraft mounts were installed without shields. These were added in 1963. The gun housings are fibreglass. (Jane's Fighting Ships 1963-64 shows photographs taken in 1962 and 1963 respectively of Skeena and Assiniboine with these.)

Machinery

The vessels of the St. Laurent class had two Babcock & Wilcox water tube boilers installed providing 600 PSI (4.1 MPa, 42 kgf/cm²) at 850 °F (454.4 °C).

The steam produced by these boilers was directed at two geared steam turbines which powered two shafts, providing 30,000 HP (22 MW) to drive the ship at a maximum speed of 28.5 knots (52.8 km/h). By the early 1990s, the quoted maximum speed was only 27 kt.

"Propelling machinery is of British design. Yarrow & Co Ltd, Scotstoun, Glasgow, received an order from Canadian Vickers for the supply of a complete set of machinery for the St. Laurent, the other ships being supplied with machinery manufactured in Canada. The main turbines and machinery are of English Electric design."

DDH conversion

The advent of nuclear-powered attack submarines in the late 1950s prompted RCN leaders to assess the new threat they posed. Although these craft were noisier than older submarines and could therefore be detected at longer ranges, they were also capable of 30 knots (56 km/h) while submerged, which was faster than the top speed of the St. Laurents at 28.5 knots (52.8 km/h). Some RCN leaders harbored serious doubts that the destroyers could effectively pursue and destroy such fast vessels, even when operating in pairs. During a 25 February 1959 meeting of the Naval Board, it was decided that the Navy would counter the new threat by outfitting destroyers for helicopter operation.

The RCN had examined the feasibility of operating ASW helicopters from small escorts when it modified the Prestonian-class frigate HMCS Buckingham (FFE 314) in mid-1956 with a temporary helicopter landing platform fitted the quarterdeck. Trials held in October 1956 using a Sikorsky HO4S-3 were successful, and a larger temporary helicopter landing platform was installed in the new destroyer escort HMCS Ottawa (DDE 229) in August 1957. Operational trials were conducted using an RCAF Sikorsky S-58, a substantially larger and heavier aircraft than the HO4S, and the success of these tests led to approval of the concept.

To achieve the goal, the RCN needed a helicopter capable of all-weather day-and-night operations with a heavy weapons load- capabilities the HO4S lacked- and a means to handle and secure the aircraft on the landing platform in rough seas. Trials showed landing was not the major concern: deck handling was. Manpower alone was insufficiently quick or certain in all conditions. During the 1957 trials aboard Ottawa, it had taken 30 tense minutes to secure the S-58 to the deck during nighttime operations in rough seas. The deck handling issue was addressed by the invention of the beartrap. The Navy came up with the solution, and contracted Fairey Aviation of Dartmouth, NS, to produce it. Fairey's prototype was installed in HMCS Assiniboine during her 1962-63 conversion. By keeping the aircraft secure, the beartrap eliminated the need for deck handling from landing to the hangar, or from hangar to takeoff.

"In conjunction with the helicopter carrying features and hangar facilities, roll-damping fins were added to the destroyers being so built or converted. These fins reduce the roll of the ship and aid landing and take-off operations during rough weather."

Initial studies identified two helicopters that met the upcoming requirements- the Sikorsky S-61 (HSS-2) Sea King and the Kaman K-20 (HU2K). The Sea King was ultimately chosen in December 1961.

All seven St Laurents were fitted with helicopter platforms and SQS 504 Variable Depth Sonar (VDS). St Laurent was equipped with VDS late in 1961, the helicopter platform to be added later. When ships were fitted with the helicopter platform, the single funnel was altered to twin stepped funnels to permit the forward extension of the helicopter hangar. Stabilizing systems were added to allow for helicopter recovery in any sea conditions, and a single CH-124 was carried. To make room for the helicopter deck, the aft 3 in (76 mm) mount and one of the Limbos were removed.

Assiniboine was the first in the class to receive the full upgrade, re-commissioning as a DDH on 28 June 1963. On 27 November 1963, her new platform was used for the first operational landing of a production CHSS-2 Sea King, and her beartrap landing system was used operationally for the first time a week later.

DELEX program

In the late 1970s, under the Destroyer Life Extension (DELEX) program was commissioned to upgrade ten of the St. Laurent and Restigouche-class ships with new electronics, machinery, and hull upgrades and repairs. The intent of DELEX was to extend the life of these ships for another 15 years of service while the Halifax-class frigates were being designed and built as part of the Canadian Patrol Frigate Program.

DELEX included the installation of a Naval Tactical Data System (NTDS) known as the Automatic Data Link Plotting System (ADLIPS), as well as the Canadian Electronic Warfare System (CANEWS), and a new communication suite.

The DELEX program was very successful as it allowed older ships to participate in a modern electronic battle field using tactical data links between ships and aircraft.

Ships

Note that pennant numbers were originally prefixed DDE but were changed to DDH in the early 1960s.

Royal Canadian Navy - St. Laurent class - Canadian Forces Maritime Command
Ship	Original Pennant Number	Builder	Laid Down	Launched	Commissioned	Refits Completed		Paid Off	Fate
						DDH	DELEX
HMCS St. Laurent	DDE 205	Canadian Vickers Ltd., Montreal	22 November 1950	30 November 1951	29 October 1955	4 October 1963	Never	14 June 1974	Placed in category C reserve instead of undergoing DELEX. Paid off, sold in 1979. Foundered and sank off Cape Hatteras on 12 January 1980 while being towed to breakers in Texas.
HMCS Saguenay	DDE 206	Halifax Shipyards Ltd., Halifax	4 April 1951	30 July 1953	15 December 1956	14 May 1965	23 May 1980	26 June 1990	Sold 1990. Scuttled as an artificial reef off Lunenburg, Nova Scotia.
HMCS Skeena	DDE 207	Burrard Dry Dock Ltd., North Vancouver	1 June 1951	19 August 1952	30 March 1957	14 August 1965	20 November 1981	1 November 1993	For disposal 1994. Sold for scrap 1996.
HMCS Ottawa	DDE 229	Canadian Vickers Ltd., Montreal	8 June 1951	29 April 1953	10 November 1956	21 October 1964	26 November 1982	31 July 1992	Sold 1992. Scrapped in 1994.
HMCS Margaree	DDE 230	Halifax Shipyards Ltd., Halifax	12 September 1951	29 March 1956	5 October 1957	15 October 1965	28 November 1980	2 May 1992	Scrapped 1994.
HMCS Fraser	DDE 233	Burrard Dry Dock Ltd., North Vancouver	11 December 1951	19 February 1953	28 June 1957	22 October 1966	28 May 1982	5 October 1994	Fraser was used as a testbed in the 1980s for technologies used on the Halifax-class frigate. Placed for disposal in 1994; laid up in Bridgewater, Nova Scotia until 2009 when DND regained possession and moved her to Halifax. Scrapped 2011.
HMCS Assiniboine	DDE 234	Marine Industries Ltd., Sorel	19 May 1952	12 February 1954	16 August 1956	28 June 1963	16 November 1979	14 December 1988	Harbour training ship at Halifax 1989. Scrapped in 1995.

Significance

In 1997, the Historic Sites and Monuments Board of Canada recognized the St. Laurent Class as being historically significant to Canadians and in 2000 installed a bronze plaque aboard HMCS Fraser which reads:

St. Laurent Class of Canadian Warship

The pride of the Canadian Navy during the Cold War, these anti-submarine escorts were the first naval vessels conceived and built in Canada. Designed in 1948-1949, they influenced naval construction internationally with their smooth above-water surfaces and distinctive convex deck. They could also be sealed to protect crews against biological and radioactive threats. All seven St. Laurent-class ships were modified during the 1960s to carry helicopters and enhance their anti-submarine capability. Launched in 1953, the HMCS Fraser is the last surviving example of this innovative class of warship.

— National Historic Site plaque

References

• Canadian Navy of Yesterday & Today: St. Laurent class destroyer escort
• Chumbley, Stephen and Gardner, Robert (Ed.) Conway's All the World's Fighting Ships, 1947-1995. Conway Maritime Press, 1995. ISBN 0-85177-605-1.
• Couhat, Jean Labayle, Combat Fleets of the World 1978-79 Arms and Armour Press, 1978.
• Friedman, Norman, The Postwar Naval Revolution, Naval Institute Press, 1986. ISBN 0-87021-952-9.
• Janes Fighting Ships 1963-64
• Sharpe, Richard Janes Fighting Ships 1992-92, Janes Information Group, 1992. ISBN 0-7106-0983-3.
• Soward, Stuart E. Hands to Flying Stations, a Recollective History of Canadian Naval Aviation, Volume II. Victoria, British Columbia: Neptune Developments, 1995. ISBN 0-9697229-1-5.
• Crowsnest Magazine - Vol 17, Nos 3 and 4 March-April 1965